DESIGN AND FABRICATION OF THE ESS-BILBAO RFQ PROTOTYPE MODELS

As part of the development of the ESS-Bilbao Accelerator in Spain, two different sets of radio frequency quadrupole (RFQ) models have been developed. A set of four oxygen free high conductivity copper weld test models has been designed and manufactured, in order to test different welding methods as well as other mechanical aspects involved in the fabrication of the RFQ. A 352.2MHz four vane RFQ cold model, 1 meter in length, has also been designed and built in Aluminum. These models serve as a good test bench to investigate the validity of different finite element analysis (FEA) software packages. This is a critical part, since the design of the final RFQ will be based on such simulations. The cold model also includes 16 slug tunersand8 coupler/pick-upports,whichwill allowthe use of the bead-pull perturbation method to measure the electric field profile, Q-value and resonant modes. In order to investigate fabrication tolerances, the cold model also includes a longitudinal test modulation in the vanes, which is similar to the one intended for the final RFQ. In addition, it represents a useful tool to explore the influence of the modulations in the electromagnetic design.